Position and Warning Systems Which of the following are some uses for a DCselsyn system? 1. Indicates position of retractable landing gear. 2. Indicates the angle of incidence of an aircraft. 3. Indicates the altitude of an aircraft. 4. Indicates cowl flaps or oil cooler door position. 5. Indicates fuel quantity. 6. Indicates the rate of climb of an aircraft. 7. Indicates position of wing flaps. a. 1, 4, 5, 7. b. 2, 3, 4, 5. c. 2, 3, 5, 6.